/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alipay.sofa.ark.loader.jar;

import com.alipay.sofa.ark.loader.data.RandomAccessData;

import java.io.IOException;
import java.util.Calendar;
import java.util.GregorianCalendar;

/**
 * A ZIP File "Central directory file header record" (CDFH).
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 * @see <a href="http://en.wikipedia.org/wiki/Zip_%28file_format%29">Zip File Format</a>
 */

final public class CentralDirectoryFileHeader implements FileHeader {

    private static final AsciiBytes SLASH      = new AsciiBytes("/");

    private static final byte[]     NO_EXTRA   = {};

    private static final AsciiBytes NO_COMMENT = new AsciiBytes("");

    private byte[]                  header;

    private int                     headerOffset;

    private AsciiBytes              name;

    private byte[]                  extra;

    private AsciiBytes              comment;

    private long                    localHeaderOffset;

    public CentralDirectoryFileHeader() {
    }

    public CentralDirectoryFileHeader(byte[] header, int headerOffset, AsciiBytes name,
                                      byte[] extra, AsciiBytes comment, long localHeaderOffset) {
        super();
        this.header = header;
        this.headerOffset = headerOffset;
        this.name = name;
        this.extra = extra;
        this.comment = comment;
        this.localHeaderOffset = localHeaderOffset;
    }

    public void load(byte[] data, int dataOffset, RandomAccessData variableData,
                     int variableOffset, JarEntryFilter filter) throws IOException {
        // Load fixed part
        this.header = data;
        this.headerOffset = dataOffset;
        long nameLength = Bytes.littleEndianValue(data, dataOffset + 28, 2);
        long extraLength = Bytes.littleEndianValue(data, dataOffset + 30, 2);
        long commentLength = Bytes.littleEndianValue(data, dataOffset + 32, 2);
        this.localHeaderOffset = Bytes.littleEndianValue(data, dataOffset + 42, 4);
        // Load variable part
        dataOffset += 46;
        if (variableData != null) {
            data = Bytes.get(variableData.getSubsection(variableOffset + 46, nameLength
                                                                             + extraLength
                                                                             + commentLength));
            dataOffset = 0;
        }
        this.name = new AsciiBytes(data, dataOffset, (int) nameLength);
        if (filter != null) {
            this.name = filter.apply(this.name);
        }
        this.extra = NO_EXTRA;
        this.comment = NO_COMMENT;
        if (extraLength > 0) {
            this.extra = new byte[(int) extraLength];
            System.arraycopy(data, (int) (dataOffset + nameLength), this.extra, 0,
                this.extra.length);
        }
        if (commentLength > 0) {
            this.comment = new AsciiBytes(data, (int) (dataOffset + nameLength + extraLength),
                (int) commentLength);
        }
    }

    public AsciiBytes getName() {
        return this.name;
    }

    @Override
    public boolean hasName(String name, String suffix) {
        return this.name.equals(new AsciiBytes(suffix == null ? name : name + suffix));
    }

    public boolean isDirectory() {
        return this.name.endsWith(SLASH);
    }

    @Override
    public int getMethod() {
        return (int) Bytes.littleEndianValue(this.header, this.headerOffset + 10, 2);
    }

    public long getTime() {
        long date = Bytes.littleEndianValue(this.header, this.headerOffset + 14, 2);
        long time = Bytes.littleEndianValue(this.header, this.headerOffset + 12, 2);
        return decodeMsDosFormatDateTime(date, time).getTimeInMillis();
    }

    /**
     * Decode MS-DOS Date Time details. See
     * <a href="http://mindprod.com/jgloss/zip.html">mindprod.com/jgloss/zip.html</a> for
     * more details of the format.
     * @param date the date part
     * @param time the time part
     * @return a {@link Calendar} containing the decoded date.
     */
    private Calendar decodeMsDosFormatDateTime(long date, long time) {
        int year = (int) ((date >> 9) & 0x7F) + 1980;
        int month = (int) ((date >> 5) & 0xF) - 1;
        int day = (int) (date & 0x1F);
        int hours = (int) ((time >> 11) & 0x1F);
        int minutes = (int) ((time >> 5) & 0x3F);
        int seconds = (int) ((time << 1) & 0x3E);
        return new GregorianCalendar(year, month, day, hours, minutes, seconds);
    }

    public long getCrc() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 16, 4);
    }

    @Override
    public long getCompressedSize() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 20, 4);
    }

    @Override
    public long getSize() {
        return Bytes.littleEndianValue(this.header, this.headerOffset + 24, 4);
    }

    public byte[] getExtra() {
        return this.extra;
    }

    public AsciiBytes getComment() {
        return this.comment;
    }

    @Override
    public long getLocalHeaderOffset() {
        return this.localHeaderOffset;
    }

    @Override
    public CentralDirectoryFileHeader clone() {
        byte[] header = new byte[46];
        System.arraycopy(this.header, this.headerOffset, header, 0, header.length);
        return new CentralDirectoryFileHeader(header, 0, this.name, header, this.comment,
            this.localHeaderOffset);
    }

    public static CentralDirectoryFileHeader fromRandomAccessData(RandomAccessData data,
                                                                  int offset, JarEntryFilter filter)
                                                                                                    throws IOException {
        CentralDirectoryFileHeader fileHeader = new CentralDirectoryFileHeader();
        byte[] bytes = Bytes.get(data.getSubsection(offset, 46));
        fileHeader.load(bytes, 0, data, offset, filter);
        return fileHeader;
    }

}
